Correcting typewriters have long been known which could remove incorrect characters and allow entry of correct ones by following an appropriate, but lengthy, sequence of keystrokes. With the advent of recording typewriters (paper tape, magnetic tape, magnetic card, etc.) it became possible to reduce the number of keystrokes required, but insertion of additional characters was still a cumbersome, time-consuming procedure. "Dictionary" typewriters such as those disclosed in the related applications (referred to hereinafter as "Reference I" inasmuch as they are practically identical as to specification and figures) have recently appeared on the market. These have an electronic memory for storing one or more pages of entered text in a random access section of the memory (RAM), together with a lengthy list of commonly-used words--35,000 say, all words in this list being correctly spelled and stored in compressed form in a read-only section of the memory ROM and a comparison unit monitoring successive text entries and emitting a visual or auditory signal when comparison of entered characters (a fragment of a word) with the list of words in the memory (the "dictionary") indicates a disagreement in the spelling of the entered word fragment. That signal indicate the typist's entry to be erroneous, such that spelling of the just-entered word or fragment of same should be checked. In more powerful versions, the typewriter have an associated display unit, where prior text (including the incorrect word or fragment) may be visually presented before being printed.
While the foregoing improvement have done much to enhance the quality of communications prepared by poor spellers, the efficiency of typewriter use is still not optimum because time spent finding a printed dictionary and looking up the correct spelling of the word or fragment would be more productively spent as further typing. Thus, there is need for reducing time spent in correction of errors and for fully utilizating correct information stored in compressed form in the memory; before or after printing occurs, of course.